1. Field of the Invention
The present invention concerns the management of channel descriptors and more particularly, the management of such descriptors to improve the efficiency of mobile stations.
2. Description of the Related Art
The Institute of Electrical and Electronics Engineers (IEEE) 802.16e standard calls for the periodic transmission of channel descriptors, such as downlink channel descriptors (DCD) and uplink channel descriptors (UCD), to mobile subscriber stations (MSS). The DCD and the UCD contain information that relates to, among other things, the modulation schemes employed by the base station (BS) in communication with the MSS. In accordance with the 802.16e standard, the intervals between DCD and UCD transmissions may be relatively long, up to ten seconds, in fact.
There may be times, however, when the BS changes its modulation schemes. As an example, the MSS may monitor a DCD or UCD counter to determine when the BS has changed these schemes. If the MSS detects the modification through the DCD or UCD counter, the MSS may determine when the next DCD containing the new modulation information will arrive by processing a broadcast control pointer information element (IE). Given the long intervals between DCDs or UCDs mentioned above, this time may be nearly ten seconds. During this time, the MSS may not be able to decode any information that it receives from the BS or to transmit to the BS using a modulation that is acceptable to the BS, which severely affects the performance of the MSS.